Airborne particles below 2.5 μm in diameter, PM2.5, are associated with increased morbidity and mortality. This same size class of particles also influences global climate, through absorption and scattering of light and through effects on the formation, albedo and lifetime of clouds. The smallest of these particles, below about 100 nm in diameter are associated with the emerging field of nanotechnology, and the occupational health risks associated with manufacturing and using nano materials.
Time-resolved information on the chemical, biological and elemental composition of the fine, airborne particles found in the atmosphere is needed to understand their sources, their impact on public health, and their role in global climate. In industrial environments, similar time-resolved compositional information is needed to protect worker health, to understand and monitor industrial processes.
There is a paucity of daily, time-resolved composition data for atmospheric particles. While gaseous pollutants such as ozone are measured continuously at 1200 sites throughout the country, atmospheric particle chemistry data are incomplete, generally limited to 24-hour averages once every third or sixth day, with just 380 sites nationwide. Complete data sets, with daily measurements, are needed for epidemiology studies. Sub-daily time resolution is critical to understanding sources, transport and transformation, and to evaluating exposure. Yet to date, such measurements are too costly for wide-spread deployment, nor is current technology appropriate for time-resolved personal or micro-environmental measurements. Moreover, in the field of industrial hygiene particle measurements are generally limited to gravimetric assays on integrated, 8-hour filter collection. Time-resolved chemical composition information is not readily available for worker protection. Accordingly, instruments that can provide concentrated, sequential collection of airborne particles are expected to provide useful assessments of health risks due to inhalation of atmospheric particles, and of nanoparticle exposure in the workplace, as well as tools to better assess the role of atmospheric particles in global radiation balance.